2 Different Rigs, Copy animation using key bones?
All animation data are stored in a datablock called &quot;Action&quot;: you can access it in the dopesheet window, changing the menu from &quot;dopesheet&quot; to &quot;action&quot;. In the proposed situation, they are keyframes data reporting loc, rot and scale values of bones.
As long as the names of all bones are the same, the action can be applied to many different armatures, and you can (i.e.) apply a location offset to a main bone for having them working &quot;in parallel&quot;, for instance.
Be aware that if the names of the bones are the same but their position and size is different, the animation can give unexpected behaviours.
All animation data referring to a bone name not found in the armature will be simply ignored.
You can &quot;code&quot; rename as occur to re-assign them in single bone strings (dopesheet/actions).
So select the second armature (which could be a copy of the first) go to the action editor window, assign the action, and both armatures will move in Sync.